I wasn't recommending against Chinese phones at all. And I made the mistake of assuming OP/anyone reading was in the US, when they might be from Europe or elsewhere where the phones work fine.
But you can find a lot of other people experiencing poor reception issues with imported phones. It isn't just me.
I said I have a OnePlus 12 and its great. But it has full band support because OnePlus makes domestic versions of phones in other markets.
Last I looked on GSM Arena, there's like 1 Xiaomi device that has this, and many other Chinese brands are also lacking the specific bands.
I think thats where our disconnect is. I'm talking about the hardware in the phone itself.
You shouldn't have those issues because your OnePlus is a US version made for US markets, so has the proper bands/antennae to work fully on our networks and take advantage of things like 5g.
The same phones sold in China are not likely to have these to save money because they aren't necessary.
It's not "Chinese phones bad", but "imported phones usually lack US-specific hardware". OnePlus is a notable exception to this because they make phones for the US, unlike companies like Xiaomi. Which is why I keep mentioning that buying from their US store is fine.
This is also why imported phones may have trouble with activation. They're not recognized by some US carriers or blacklisted, like Huawei, to where they don't work or you may need to activate the SIM in a compatible phone and then swap it to your real one.